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docs: enumerate possible directory ftype values

Message ID 20161219221247.GB5487@birch.djwong.org
State Not Applicable
Headers show

Commit Message

Darrick J. Wong Dec. 19, 2016, 10:12 p.m. UTC
We don't actually list the ftype constants, so do that.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
 .../XFS_Filesystem_Structure/directories.asciidoc  |   29 ++++++++++++++++++++
 1 file changed, 29 insertions(+)

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diff mbox


diff --git a/design/XFS_Filesystem_Structure/directories.asciidoc b/design/XFS_Filesystem_Structure/directories.asciidoc
index 1758c4e..9bb50bd 100644
--- a/design/XFS_Filesystem_Structure/directories.asciidoc
+++ b/design/XFS_Filesystem_Structure/directories.asciidoc
@@ -26,6 +26,35 @@  directories.
 * An +offset+ or +tag+ used for iterative readdir calls.
+* If the +XFS_SB_FEAT_INCOMPAT_FTYPE+ feature flag is set, each
+directory entry contains an +ftype+ field that caches the inode's type
+to avoid having to perform an inode lookup.
+.ftype values
+| Flag				| Description
+Entry points to an unknown inode type.  This should never appear on disk.
+Entry points to a file.
+| +XFS_DIR3_FT_DIR+ |
+Entry points to another directory.
+Entry points to a character device.
+Entry points to a block device.
+Entry points to a FIFO.
+Entry points to a socket.
+Entry points to a symbolic link.
+| +XFS_DIR3_FT_WHT+ |
+Entry points to an overlayfs whiteout file.  This (as far as the author
+knows) has never appeared on disk.
 All non-shortform directories also contain two additional structures: ``leaves''
 and ``freespace indexes''.